1 Corinthians 5:8 WEB

⁶  Your boasting is not good. Don't you know that a little yeast leavens the whole lump?

⁷  Purge out the old yeast, that you may be a new lump, even as you are unleavened. For indeed Christ, our Passover, has been sacrificed in our place.

⁸  Therefore let us keep the feast, not with old yeast, neither with the yeast of malice and wickedness, but with the unleavened bread of sincerity and truth.

⁹  I wrote to you in my letter to have no company with sexual sinners;

¹⁰  yet not at all meaning with the sexual sinners of this world, or with the covetous and extortioners, or with idolaters; for then you would have to leave the world.